This invention relates to a control device, a control method, a radio communication apparatus and computer-readable medium, which are preferably applied to, for example, a wireless network.
With advances in the widespread use of portable devices such as a notebook personal computer, an electronic pocketbook, various analog and digital interfaces have made progress in wireless form and speed-up in recent years. In regard to computer fields in particular, wireless and speed-up efforts grow widespread. A construction of a non-contact connection-based network has been put forward between portable devices as well as tabletop devices by using techniques typified by a wireless LAN (local area network) and IrDA (infrared data association).
For example, the wireless LAN makes it possible to provide communications between a plurality of nodes through the use of an access control protocol called xe2x80x9cCSMA (carrier sense multiple access)xe2x80x9d. Further, for example, the IrDA allows communications to be made between two nodes through the use of an access control protocol called xe2x80x9cIrLAP (infrared link access protocol)xe2x80x9d.
However, when such recent high-speed serial buses as typified by a USB (universal serial bus), an IEEE1394, etc., are brought into wireless form, these access techniques cannot be utilized as they are. As already well known, these high-speed serial buses support a transfer system called,an isochronous transfer to transfer data of applications placing importance on real time, such as AV (audio-visual) data. This isochronous transfer is a transfer method for assuring a transfer width and time of data thereby to implement a transfer of a predetermined amount of data in a predetermined cycle, which is of importance to the real time transfer of a device.
In order to implement such a transfer method with a wireless network constructed by a plurality of nodes, frequent switching between outgoing or sending nodes is required to ensure transfer widths and transfer time intervals of each individual data sent from the plurality of nodes. Therefore, the access control protocol of the above-described IrLAP used in a one-to-one relationship cannot be used as it is. Further, the access control protocol called the above-described CSMA for detecting a state of non-use of a space and thereafter ensuring the corresponding transfer width cannot be used either as it is.
In order to implement the isochronous transfer of the high-speed serial bus such as USB or IEEE1394 by wireless, the frequent switching between the sending nodes is needed as described above and a network structure is required in which one node takes charge of sending or outgoing control and information management.
Further, these high-speed serial buses respectively have the function of being capable of changing their states with power-on. Since one input/output plug generally bears one connection when nodes are connected to one another with a cable, a change in connection can be recognized based on a change in the electric characteristic of the plug. In the case of a wireless connection, however, there is a high possibility that one input/output device will bear a plurality of connections. Thus, the device encounters difficulties in recognizing each connection change by a change in the electric characteristic.
Further, when a number of nodes connected to a serial bus are changed in the IEEE1394, a reset processing of network configuration called xe2x80x9cbus resetxe2x80x9d is carried out. In this case, during this reset processing, all the streams of packets sent to and received from the network are required to stop. Thus, a user cannot use this network during such a period.
It is conceivable that, as the portable devices used in wireless network have such a property that they can be easily carried, they might be newly entered into the already established network when they are powered on or they might be carried out of an area enabling a communication when they are already connected with the network. In this case, there increases or decreases the number of devices connected with the network, the network needs carry out a reset processing to grasp the configuration of the whole network. Thus, this brings about the similar problem in the case described above that the network cannot be used during such a reset period.
An object of the present invention is to eliminate the need for resetting the whole network when there increases or decreases the number of devices connected with the network.
A control device according to this invention is a control device for controlling pieces of controlled apparatus performing communications within a network, comprising a holding means for holding a predetermined number of identifier to be allocated to the controlled apparatus connected with the network, and an allocating means for allocating the identifier not yet allocated among the identifiers held in the holding means, when the controlled apparatus is newly entered into the network, to the controlled apparatus. Another control device according to this invention is a control device further comprising deallocating mans for deallocating the identifier allocated to the controlled apparatus when the controlled apparatus is removed from the network.
A control method according to the invention is a control method of a control device for controlling pieces of controlled apparatus performing communications within a network, comprising a holding step for holding a predetermined number of identifier to be allocated to the controlled apparatus connected with the network, and an allocating step for allocating the identifier not yet allocated among the identifiers held in the holding step, when new controlled apparatus is connected with into the network, to the new controlled apparatus. Another control method according to this invention is a control method further comprising deallocating step for deallocating the identifier allocated to the controlled apparatus when the controlled apparatus is removed from the network.
A computer-readable medium according to the invention is a computer-readable medium for recording a program for allowing a computer in a control device for controlling pieces of controlled apparatus performing communications within a network to carry out a holding step for holding a predetermined number of identifier to be allocated to the controlled apparatus connected with the network, and an allocating step for allocating the identifier not yet allocated among the identifiers held in the holding step, when new controlled apparatus is connected with the network, to the new controlled apparatus. Another computer-readable medium according to the invention is a computer-readable medium for further recording a program for allowing a computer to carry out deallocating step for deallocating the identifier allocated to the controlled apparatus when the controlled apparatus is removed from the network.
Further, a radio communication apparatus according to this invention is a radio communication apparatus comprising one control device and one or more pieces of controlled apparatus controlled by the control device and performing communications between the respective device and apparatus by radio, wherein the control device includes a holding means for holding a predetermined number of identifier to be allocated to the controlled apparatus, and an allocating means for allocating the identifier not yet allocated among the identifiers held in the holding means, when new controlled apparatus is entered into the network, to the new controlled apparatus.
In the present invention, the control device (a control apparatus) for controlling pieces of controlled apparatus performing communications within a network, holds a predetermined number of identifier to be allocated to the controlled apparatus connected with the network. Further, the control device allocates the identifier not yet allocated among the held identifiers, when the controlled apparatus is newly entered into the network, to the controlled apparatus and deallocates the identifier allocated to the controlled apparatus when the controlled apparatus is removed from the network. Thus, the control device may grasp the configuration of the whole network easily when the controlled apparatus is entered into and removed from the network and then, this eliminates the needs for resetting the whole network.